:root {
    --primary: #2A9D8F;
    --dark: #264653;
    --light: #e9ecef;
    --font-size-base: 1rem;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}


html, body {
    margin: 0;
    padding: 0;
    width: 100%;
    min-height: 100vh; /* 确保页面至少有视口高度 */
}

body {
    font-family: 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: #333;
    overflow-x: hidden;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    text-decoration: none;
    color: inherit;
}

.nav-container {
    display: flex;
    justify-content: space-between; /* 关键修改 */
    align-items: center;
    padding: 0 30px;
    height: 100px;
    background: #fff;
    border-bottom: 1px solid #f0f0f0;
}

/* 左侧logo区 */
.logo-group {
    flex: 1; /* 左侧区域占据1份空间 */
    display: flex;
    justify-content: flex-start; /* 内容左对齐 */
}
.logo-group img {
    height: 100px;
    width: auto;
    transition: transform 0.3s;
}
.logo-group img:hover {
    transform: translateY(-2px);
}

/* 中间导航区 - 调整间距 */
.nav-links {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
    position: relative;
    flex: 0 0 auto; /* 中间区域不伸缩 */
    margin: 0 auto; /* 水平居中 */
}

.nav-item {
    position: relative;
    margin: 0 50px;
}

.nav-item > a {
    color: #000;
    text-decoration: none;
    font-size: 18px;
    padding: 20px 0;
    display: block;
}

.nav-item:not(:last-child)::after {
    content: "|";
    position: absolute;
    right: -50px; /* 等于margin-right的负值 */
    color: #999;
    font-size: 10px;
    top: 50%;
    transform: translateY(-50%);
    width: 10px;
    text-align: center;
}

.dropdown {
    position: relative; /* 新增定位基准 */
}

/* 下拉菜单样式 */
.dropdown-content {
    display: none;
    position: absolute;
    top: 73px; /* 紧贴主菜单下方 */
    left: 50%;
    transform: translateX(-50%);
    background: white;
    box-shadow: 0 8px 16px rgba(0,0,0,0.1);
    border-radius: 8px;
    min-width: 180px;
    z-index: 1001;
    padding: 10px 0;
    /* 添加悬停缓冲区 */
    margin-top: 10px;  /* 与主菜单的间隙 */
}

.dropdown:hover .dropdown-content {
    display: block;
    opacity: 1;
    visibility: visible;
}

/* 创建透明过渡区域 */
.dropdown-content::before {
    content: '';
    position: absolute;
    top: -15px; /* 覆盖上方间隙 */
    left: 0;
    width: 100%;
    height: 15px; /* 悬停过渡区高度 */
    background: transparent;
}

.dropdown-content a {
    color: #000;
    text-decoration: none;
    font-size: 13px;
    padding: 12px 20px;
    display: block;
    text-align: center;
    transition: all 0.2s;
    position: relative;
}

.dropdown-content a:hover {
    background: #f8f9fa;
}

/* 调整分隔线位置 */
.dropdown::after {
    content: "|";
    position: absolute;
    right: -50px;
    color: #999;
    font-size: 10px;
    top: 50%;
    transform: translateY(-50%);
    width: 10px;
    text-align: center;
}

/* 右侧功能区 */
.right-group {
    display: flex;
    align-items: center;
    gap: 20px;
    flex: 1; /* 右侧区域占据1份空间 */
    justify-content: flex-end; /* 内容右对齐 */
}

.promo-logo {
    height: 60px;
    width: auto;
    transition: transform 0.3s;
}
.promo-logo:hover {
    transform: scale(1.05);
}
.lang-switch {
    display: flex;
    gap: 5px;
    background: #f5f5f5;
    border-radius: 15px;
    padding: 3px;
}


.lang-switch a {
    text-decoration: none;
    color: white;
    font-size: 14px;
    padding: 5px 12px;
    border-radius: 12px;
    transition: all 0.3s;
}



.lang-switch a.lang-a {
    color: #fff;
    background: black;
    font-weight: 500;
}

.lang-switch a.active:hover {
    background: black;
}





/* 返回顶部按钮样式 */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background-color: #ccc; /* 默认灰色 */
    color: white;
    border: none;
    border-radius: 50%;
    width: 40px;
    height: 40px;
    font-size: 24px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0; /* 默认隐藏 */
    visibility: hidden; /* 默认隐藏 */
    transition: opacity 0.3s, visibility 0.3s, background-color 0.3s; /* 添加背景色过渡 */
    z-index: 1000; /* 确保在最顶层 */
}
.back-to-top.show {
    opacity: 1; /* 显示 */
    visibility: visible; /* 显示 */
}
.back-to-top:hover {
    background-color: black; /* 悬停时变为黑色 */
}

.back-to-top::after {
    content: "↑";
    font-size: 24px;
    font-weight: bold;
}


/* 页脚样式 */
.site-footer {
    background: rgba(0, 0, 0, 0.8); /* 与头部导航栏颜色一致 */
    padding: 2rem 0;
    border-top: 1px solid #333; /* 顶部边框 */
}

.footer-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between; /* 改为两端对齐 */
    align-items: flex-start; /* 新增：顶部对齐 */
}

/* 左侧：Logo 和介绍 */
.footer-left {
    flex: 0 0 35%; /* 固定左侧宽度 */
    max-width: 400px;
    padding-right: 50px; /* 创建呼吸空间 */
}



.footer-logo {
    width: 200px; /* Logo 大小 */
    height: auto;
    margin-bottom: 1rem;
    transition: opacity 0.3s; /* 添加悬停效果 */
}

.footer-logo:hover {
    opacity: 0.8; /* 鼠标悬停时透明度变化 */
}

.footer-description {
    font-size: 1rem;
    color: #ccc; /* 浅灰色文字 */
    line-height: 1.6;
}

/* 新增样式 */
.footer-about {
    flex: 0 0 60%; /* 固定右侧宽度 */
    max-width: 700px;
    padding: 8px 0 0; /* 微调顶部对齐 */

}

.about-title {
    color: #2A9D8F;
    font-size: 1.2rem;
    margin-bottom: 1.2rem;
    font-weight: 600;
}

.about-text {
    color: #ccc;
    font-size: 0.95rem;
    line-height: 1.8;
    text-align: justify;
}
/* 右侧：一列三个链接 */
.footer-right {
    flex: 1;
    max-width: 400px; /* 限制右侧宽度 */
}

.footer-links {
    list-style: none;
    padding: 0;
}

.footer-links li {
    margin: 2.8rem 0; /* 增加链接之间的间隔 */
}

.footer-links a {
    text-decoration: none;
    color: #ccc; /* 浅灰色文字 */
    font-size: 1rem;
    transition: color 0.3s;
}

.footer-links a:hover {
    color: #2A9D8F; /* 鼠标悬停时变为品牌色 */
}

/* 版权信息 */
.copyright-notice {
    text-align: center;
    margin-top: 40px;
    padding-top: 20px;
    border-top: 1px solid white;
    font-size: 0.9rem;
    color: #888;
}

/* 新增对齐校准 */
@media (min-width: 769px) {
    .footer-logo {
        margin-top: 5px; /* 补偿LOGO图像基线 */
    }

    .about-title {
        margin-top: 0.5em; /* 标题基线对齐 */
    }
}

/* 响应式调整 */
@media (max-width: 992px) {
    .footer-left,
    .footer-about {
        flex: 0 0 50%;
        padding-right: 30px;
    }
}

@media (max-width: 768px) {
    .footer-container {
        flex-direction: column;
    }

    .footer-left,
    .footer-about {
        flex: none;
        width: 100%;
        max-width: 100%;
        padding-right: 0;
    }

    .footer-about {
        margin-top: 2rem;
    }
}